The Effect of Coadministration of GSK3640254 on the Pharmacokinetics of a Combined Oral Contraceptive Containing Ethinyl Estradiol and Levonorgestrel in Healthy Female Subjects

This is an open-label, single-sequence, 1-way drug-drug interaction study to investigate the
effect of GSK3640254 on the pharmacokinetics of a combination oral contraceptive containing
ethinyl estradiol (EE) and levonorgestrel (LNG). Effective contraception for women infected
with human immunodeficiency virus (HIV) is important in the prevention of unplanned
pregnancies. The study will consist of a screening period of 28 days, check-in (Day -4), a
run-in period and a treatment period. During the run-in period, subjects will be administered
Portia® (0.03 milligrams [mg] EE/0.15 mg LNG) once daily on Days -3 to -1. Subjects will then
be administered Portia once daily on Days 1 to 10 of treatment period A followed by
administration of Portia once daily along with GSK3640254 200 mg on Days 11 to 21 of
treatment period B. The duration of the study is approximately 8 weeks, including Screening
and Run-in. Portia is a registered trademark of Teva Pharmaceuticals USA.